The ecological implications of a Yakutian mammoth's last meal

Part of a large male woolly mammoth (Mammuthus primigenius) was preserved in permafrost in northern Yakutia. It was radiocarbon dated to ca. 18,500 ¹⁴C yr BP (ca. 22,500 cal yr BP). Dung from the lower intestine was subjected to a multiproxy array of microscopic, chemical, and molecular techniques to reconstruct the diet, the season of death, and the paleoenvironment. Pollen and plant macro-remains showed that grasses and sedges were the main food, with considerable amounts of dwarf willow twigs and a variety of herbs and mosses. Analyses of 110-bp fragments of the plastid rbcL gene amplified from DNA and of organic compounds supplemented the microscopic identifications. Fruit-bodies of dung-inhabiting Ascomycete fungi which develop after at least one week of exposure to air were found inside the intestine. Therefore the mammoth had eaten dung. It was probably mammoth dung as no bile acids were detected among the fecal biomarkers analysed. The plant assemblage and the presence of the first spring vessels of terminal tree-rings of dwarf willows indicated that the animal died in early spring. The mammoth lived in extensive cold treeless grassland vegetation interspersed with wetter, more productive meadows. The study demonstrated the paleoecological potential of several biochemical analytical techniques.     

Seasonal and latitudinal distribution of trace gases in the stratosphere: Results from a 2D residual circulation model

Results for minor stratospheric constituents using a 2D model with self-consistent transport parameters are reported. The meridional circulation is obtained from the output of the MIT-GIT 3D stratospheric model (Cunnold et al., 1975). Consistent data from the same model are used to evaluate the diffusive tensors following the formalism of Holton (1981) and Tung (1982). Chemical damping is consequently taken into account, so that the entire model is built in a selfconsistent manner at the least with the 3D model and no ad hoc assumptions are made with respect of transport parameters. This version of the model represents a major improvement on previous work (Pitari and Visconti, 1984), which used to much too simple chemistry. Results are compared whenever possible with available experimental data, with particular emphasis on chemical reacting species. This comparison shows in general an agreement which is qualitatively similar to the one obtained from classical Eulerian models where transport parameters are often tuned to long-lived tracers without any sound physical basis.     

In situ measurements of fine sediment infiltration (FSI) in gravel-bed rivers with a hydropeaking flow regime

The overpresence of fine sediment and fine sediment infiltration (FSI) in the aquatic environment of rivers are of increasing importance due to their limiting effects on habitat quality and use. The habitats of both macroinvertebrates and fish, especially spawning sites, can be negatively affected. More recently, hydropeaking has been mentioned as a driving factor in fine sediment dynamics and FSI in gravel-bed rivers. The primary aim of the present study was to quantify FSI in the vertical stratigraphy of alpine rivers with hydropeaking flow regimes in order to identify possible differences in FSI between the permanently wetted area (during base and peak flows) and the so-called dewatering areas, which are only inundated during peak flows. Moreover, we assessed whether the discharge ratio between base and peak flow is able to explain the magnitude of FSI. To address these aims, freeze-core samples were taken in eight different alpine river catchments. The results showed significant differences in the vertical stratification of FSI between the permanently wetted area during base flow and the dewatering sites. Surface clogging occurred only in the dewatering areas, with decreasing percentages of fine sediments associated with increasing core depths. In contrast, permanently wetted areas contained little or no fine sediment concentrations on the surface of the river bed. Furthermore, no statistical relationship was observed between the magnitude of hydropeaking and the sampled FSI rate. A repeated survey of FSI in the gravel matrix revealed the importance of de-clogging caused by flooding and the importance of FSI in the aquatic environment, especially in the initial stages of riparian vegetation establishment. © 2018 The Authors. Earth Surface Processes and Landforms published by John Wiley & Sons Ltd.     

Impact of projected climate change on hydrologic regime of the Upper Paraguay River basin

We present an assessment of climate change impacts on the hydrologic regime of the 600,000 km² Upper Paraguay River basin, located in central South America based on predictions of 20 Atmospheric/Ocean General Circulation Models (AOGCMs). We considered two climate change scenarios from the Intergovernmental Panel on Climate Change (IPCC) and two 30-years time intervals centered at 2030 and 2070. Projected temperature and precipitation anomalies estimated by the AOGCMs for the study site are spatially downscaled. Time series of projected temperature and precipitation were estimated using the delta change approach. These time series were used as input to a detailed coupled hydrologic-hydraulic model aiming to estimate projected streamflow in climate change scenarios at several control points in the basin. Results show that impacts on streamflow are highly dependent on the AOGCM used to obtain the climate predictions. Patterns of temperature increase persist over the entire year for almost all AOGCMs resulting in an increase in the evapotranspiration rate of the hydrological model. The precipitation anomalies show large dispersion, being projected as either an increase or decrease in precipitation rates. Based on these inputs, results from the coupled hydrologic-hydraulic model show nearly one half of projections as increasing river discharge, and other half as decreasing river discharge. If the mean or median of the predictions is considered, no discernible change in river discharge should be expected, despite the dispersion among results of the AOGCMs that reached +/?10 % in the short horizon and +/? 20 % in the long horizon, at several control points.     

Zur Geomorphogenie Anatoliens

Ohne Zusammenfassung     

Eo-Alpine HP metamorphism in the Permian intrusives from the steep belt of the central Alps (Languard-Campo nappe and Tonale Series)

Abstract

Diorites and granitoids that intruded the Upper Austroalpine units of the central Alps during the Permian display map-pable tectonic imprints and metamorphic transformations that were acquired during the Alpine tectonometamorphic cycle. Superposed heterogeneous deformations interacted with metamorphic re-equilibration stages and created a range of textural types that reflect local deformation gradients: coronitic transformations textures, normally foliated S-tectonites and mylonitic foliations. The three textural types are distinguished on maps recording foliation trajectories of successive deformation phases, which are correlated to the evolution of metamorphic assemblages. Tectonic deformation of Alpine age is represented by three generations of ductile syn-metamorphic structures. The mineral assemblages stable during the first Alpine deformation phase (D1) are Amp_II + P1_II + white mica, + Zo/Czo + Grt + Qtz ± Mg-Ch1 ± Ilm in metadiorites and P1_II + white mica_I + Zo/Czo + Grt + Amp_II + Qtz ± Ilm/Ttn in metagranitoids; the successive foliations D2a and D2b are defined by greenschist facies minerals. Thermobarometric estimates allow T = 500–600 °C and P = 1.1 ± 0.2 GPa conditions to be determined during D1 and T ≤ 350 °C and P ≤ 0.5 GPa during D2. Relict igneous minerals in metadiorites allow to determine intrusive conditions of T = 879 ± 110 °C and P = 0.4–0.7 GPa. Radiometric ages and P/T ratio of Alpine P_maxT_Pmax suggest that the inferred P-T-d-t path may represent the thermal state of the initial Alpine subduction stages. © 2000 Éditions scientifiques et médicales Elsevier SAS     

Monitoring, prediction, and early warning using ground-based radar interferometry

In order to define adequate prevention measures and to manage landslide emergencies, real-time monitoring is required. This paper presents two different applications of the remote sensing technique: the ground-based synthetic aperture radar interferometry, here proposed as a monitoring and early warning support for slope instability. Data acquisitions carried out through a ground-based synthetic aperture radar interferometer, operating in K_u band, installed in front of the observed slopes, are discussed. Two case studies, based on the use of the same apparatus (formerly developed by the Joint Research Center of the European Commission and by Ellegi-LiSALab srl), are reported: the first one concerns the monitoring of a large landslide, named Ruinon (Valfurva, Italy). The second one deals with the monitoring of the NW unstable slope in the Stromboli island aimed to implementing an early warning system. Acquired interferometric data are processed to provide displacements and velocity maps of the monitored area. The monitoring services ongoing on the Ruinon landslide and on Stromboli demonstrate the capability of this technique to operate in different operative settings (i.e., different phenomena and geological framework) and for different aims (monitoring for prevention, early warning, and emergency assessment). This methodology has also been proved by national and regional authorities of civil protection in order to provide a real-time monitoring for emergency management.     

A critical appraisal of the Cayconi Formation, Crucero Basin, southeastern Peru

The Cayconi Formation of the Crucero Basin, Puno Department, southeastern Peru, has been described as a 800–1000 m sequence of Oligocene and Miocene fanglomerate and lacustrine sedimentary rocks, interlayered with mafic and silicic volcanic rocks, and unconformably overlying Paleozoic and Cretaceous successions. On the basis of new field and petrological investigations, key aspects of the stratigraphic relationships of the rocks comprising this formation, and hence the viability of this lithostratigraphic name, are questioned. Thus, several sedimentary units previously assigned to the Cayconi Formation are reinterpreted as Cretaceous or older. We further argue that the formational terminology fails to accomodate the great variety of volcanic rocks, which are, moreover, disposed in isolated eruptive fields. We therefore propose establishment of the Crucero Supergroup as a broad, yet flexible framework for lithostratigraphic subdivision of the Tertiary sequences of the Cordillera Oriental of southeastern Peru. This new nomenclature accomodates the voluminous two-mica ash flow tuffs (Macusani Volcanics) and associated rocks of the Quenamari Meseta, a succession excluded from the existing lithostratigraphic classification scheme. It also permits distinction between the petrogenetically-contrasted upper Oligocene — Lower Miocene and Middle Miocene — Upper Miocene volcanic suites, which dominate, respectively, the Picotani and Quenamari Groups comprising the proposed Crucero Supergroup. Finally, the economically important granitic/rhyolitic intrusive centers cogenetic with the volcanic rocks are readily assignable to intrusive lithodemes in each group.     

Inorganic nitrogen dynamics in intertidal rocky biofilms and sediments of the Douro River estuary (Portugal)

In this study rates of oxygen, ammonium (NH₄ ⁺), nitrate (NO₃ ⁻), nitrite (NO₂ ⁻), and nitrous oxide (N₂O) fluxes, nitrogen (N) fixation, nitrification, and denitrification were compared between two intertidal sites for which there is an abundant global literature, muddy and sandy sediments, and two sites representing the rocky intertidal zone where biogeochemical processes have scarcely been investigated. In almost all sites oxygen production rates greatly exceeded oxygen consumption rates. During daylight, NH₄ ⁺ and NO₃ ⁻ uptake rates together with ammonification could supply the different N requirements of the primary producer communities at all four sites; N assimilation by benthic or epilithic primary producers was the major process of dissolved inorganic nitrogen (DIN) removal; N fixation, nitrification, and denitrification were minor processes in the overall light DIN cycle. At night, distinct DIN cycling processes took place in the four environments, denitrification rates ranged from 9 ± 2 to 360 ± 30 μmol N₂ m⁻² h⁻¹, accounting for 10–48% of the water column NO₃ ⁻ uptake; nitrification rates varied from 0 to 1712 ± 666 μmol NH₄ ⁺ m⁻² h⁻¹. A conceptual model of N cycle dynamics showed major differences between intertidal sediment and rocky sites in terms of the mean rates of DIN net fluxes and the processes involved, with rocky biofilm showing generally higher fluxes. Of particular significance, the intertidal rocky biofilms released 10 times the amount of N₂O produced in intertidal sediments (up to 17 ± 6 μmol N₂O m⁻² h⁻¹), representing the highest N₂O release rates ever recorded for marine systems. The biogeochemical contributions of intertidal rocky substrata to estuarine and coastal processes warrant future detailed investigation.